Minutes from the
Lake Superior Technical Committee Meeting
at the Marquette Biological Station
January 13, 1999
Table of Contents
List of Attendees
Agenda Item 1 - Lake Trout Model Development Workshop
Agenda Item 2 - Lake Trout Population Parameters
Agenda Item 3 - Subcommittee Reports
Agenda Item 4 - Age Determination of Lake Herring
Agenda Item 5 - Observation on Lake Herring Year Class Strength
Agenda Item 6 - Fluctuations in Abundance of Coregonines
Agenda Item 7 - Biomass of Lake Herring
Agenda Item 8 - Recruitment of Lake Herring in Lake Superior
Agenda Item 9 - Fish Health Monitoring
Agenda Item 10 - Growth Indices
Agenda Item 11 - Update from UW-Madison
Agenda Item 12 - Assignments for LSC Meeting
Agenda Item 13 - Habitat Supply Analysis
Agenda Item 14 - Isle Royale Creel Survey
Agenda Item 15 - Diet Protocol
Agenda Item 16 - Gear Selectivity
Agenda Item 17 - Bait Fish Harvest
Agenda Item 18 - Aquatic Community Monitoring
Agenda Item 19 - Fish Community Objectives
Agenda Item 20 - Aquatic Community Committee
Agenda Item 21 - Time and Place of Summer 1999 Meeting
List of Attendees:
Great Lakes Fishery Commission - Gavin Christie
Ontario Ministry of Natural Resources - Mike Petzold, Jeff Black, Bryan Henderson, Tim Johnson
Minnesota Department of Natural Resources - Don Schreiner, Ted Halpern
Great Lakes Indian Fish and Wildlife Commission - Bill Mattes
Red Cliff Fisheries Department - Mike Gallinat
Bad River Natural Resources Dept. - Rick Huber
Keweenaw Bay Indian Community - Mike Donofrio
Michigan Department of Natural Resources - Jim Peck, Shawn Sitar, Steve Scott
United States Fish and Wildlife Service - Dale Bast, Henry Quinlan, Lee Newman, Gary Klar
Chippewa/Ottawa Treaty Fishery Management Authority - Mark Ebener
Bay Mills Indian Community - Ken Gebhardt
United States Geological Survey-Biological Resources Division - Chuck Bronte
Canadian Dept. of Fisheries and Oceans - John Kelso, Rod McDonald
Wisconsin Dept. of Natural Resources - Stephen Schram
Michigan Sea Grant - Ron Kinnunen
University of Wisconsin-Madison - Chris Harvey
Michigan Technological University - Tom Drummer
Agenda Item 1 - Lake Trout
Model Development Workshop II
Ebener indicated that lake trout modeling efforts in the 1836 ceded territory of Lake Superior will be fairly advanced by the summer 1999 meeting of the LSTC, and at that time a working model can probably initially be applied to data from other areas of Lake Superior. The lake trout model developed by Chris Weeks will probably serve as the starting template for the modeling efforts in the 1836 ceded territory. The LSTC agreed to hold another workshop at our August 1999 meeting.
Agenda Item 2 - Lake Trout
LSTC members from each jurisdiction were assigned the task of compiling lake trout population parameters that are used to evaluate the need to stock lake trout in U. S. waters of Lake Superior. The specific parameters for each management unit include: annual harvests, estimates of total allowable catch (TAC), index of survival (Si) for age-7 hatchery-reared lake trout, catch per unit effort (CPUE) of wild lake trout, CPUE of wild lake trout >25 inches long, and proportion of wild lake trout >25 inches long. Si is calculated as the CPUE of age-7 in year t per 100,000 fish stocked of that year class.
Minnesota waters: Don Schreiner distributed a handout of lake trout populations parameters for management units in Minnesota waters of Lake Superior. Survival index in Minnesota declined dramatically beginning in 1996 in all units. The current percentage of wild fish is below the criteria of 50% in both MN-1 and MN-2, but above the criteria of 50% in MN-3. Nearly all the criteria for reducing stocking have been met for lake trout in MN-3, except for CPUE of wild fish >25 inches long which has declined from 1996 to 1998.
Michigan: Shawn Sitar, Mike Gallinat, and Ken Gebhardt summarized lake trout population parameters in Michigan management units MI-2, MI-3, MI-4, MI-5, MI-6, MI-7, and MI-8. Shawn reported that the survival index is below 1.0 in management units MI-3, MI-4, MI-5, MI-6, and MI-7. The proportion of wild lake trout >25 inches has ranged from 77 to 95% in these same units during 1995-1997. Abundance of wild spawners as remained fairly stable in each of those same management units over the last three years.
Mike Gallinat summarized lake trout population parameters in MI-2. The survival index in MI-2 is poor and was less than 0.4 in 1995-1998. The reported harvest represented 45-61% of the TAC for MI-2 in 1995-1998. The proportion of wild lake trout >25 inches long has ranged from 86-95% during 1995-1998, but CPUE of wild spawners >25 inches long has been declining since 1995 in MI-2.
Ken Gebhardt summarized lake trout population parameters in MI-8. MI-8 is a deferred rehabilitation zone in which 150,000 fingerling lake trout are stocked annually. Si of lake trout in MI-8 is less than 1.0 and has declined from 1996 to 1998. The proportion of wild lake trout in assessment catches increased from 21% in 1996 to 60% in 1998. The proportion of wild lake trout >25 inches long declined from 10% in 1996 to 3% in 1998, although CPUE of wild fish >25 inches long has increased slightly since 1996.
Wisconsin: Stephen Schram summarized lake trout populations parameters in WI-1 and WI-2. . Harvests are being maintained within the TAC guidelines in both WI-1 and WI-2. Si remains below 1.0 in WI-2, while in WI-1 the Si values declined dramatically in 1994 and are now less than 1.0. The proportion of wild lake trout >25 inches long has increased in WI-1 from 6% in 1990 to 49% in 1998, while in WI-2 the proportion of wild lake trout >25 inches long has ranged from 73 to 85% in 1990-1998. CPUE wild lake trout >25 inches long has been increasing or stable in WI-2 and increasing in WI-1 during 1990-1998.
Based on analysis of the lake trout population parameters the following
recommendations were made.
1) Continue stocking lake trout in MN-1 and MN-2.
2) Continue to stock MN-3 for 3-5 years, if the positive trends in CPUE of wild fish >25 inches long continues, then discontinue stocking.
3) There is no need to stock lake trout in Michigan waters of Lake Superior.
4) There is no need to stock lake trout in WI-2, and
5) Stocking should continue in WI-1.
Ontario: Mike Petzold distributed a handout illustrating harvest by zone and percent of quota harvested. In most units the harvest was below the quota. Ontario does not have a long term survey designed to estimate Si or CPUE of wild lake trout since OMNR only began spring lake trout surveys in 1997. Mike did compute Si and CPUE of wild spawners for units 28, 31, and 33. Si was 0.1 in unit 28, 0.66 in unit 31 in 1998 and 0.66 in unit 33 in 1997. CPUE of wild spawners was 1.6 in unit 28 and 1.3 in unit 31 in 1998.
Chuck Bronte updated the Si for ages 2-4 hatchery-reared lake trout caught in bottom trawls as reported in the Hansen et al. (1994) paper. Chuck computed CPUE as fish per 100 tows instead of per individual tow. The trawl data show that Si has stabilized or increased slightly since the 1986 year class. The 1993 year class had the best survival in the time series. Dale Bast reported that the 1993 year class was the first of the larger yearlings stocked into Lake Superior.
Chuck Bronte will continue to update the figure
to include the Hansen et al. (1994) data so Ebener can use the figure
in the LSTC report to the LSC.
Mike Petzold asked whether it is better to compute CPUE as the geometric mean instead of arithmetic mean. Mike indicated that the geometric mean is a more stable statistic since excessively large catches do not have as much influence on the mean as with the arithmetic mean. Another advantage of the geometric mean is that confidence limits about the mean CPUE value can be estimated. The arithmetic mean is estimated as the sum of lake trout catches divided by the sum of the effort for a management unit. The geometric mean is calculated as the mean natural logarithm of CPUE for individual lifts in a management unit. Transforming the CPUE values into natural logarithms produces a more normal distribution of CPUE. If there are zero values for CPUE just add 1 to each CPUE before transforming the value to it natural logarithm. An example of estimating the geometric mean and 95% confidence interval is provided below.
Arithmetic mean CPUE
Geometric mean of natural log
Standard deviation natural log mean
Interval estimate of natural log mean
95% confidence interval natural log mean
Geometric mean CPUE (back-transformed)
95% CI (back-transformed)
1.6 to 52.9
5.8 to 107.9
Agenda Item 3 - Subcommittee
Lee Newman distributed a revised version of the brook trout rehabilitation plan. Lee and Bob DuBois added a few streams to the list of streams where brook trout may have occurred based on suggestions they received from the various agencies. Based on comments from Ebener and other LSTC members, Lee and Bob removed the previous recommendation from the rehabilitation plan that stocking of splake be discontinued. Lee and Bob replaced the original recommendation with a recommendation to fin clip all splake stocked in Lake Superior and that agencies weigh the potential threats to brook trout caused by stocking non-indigenous or indigenous salmonines. The Brook Trout Subcommittee is adamant about discontinuing splake stocking and wants the LSTC to understand their concern.
Ebener suggested that the rehabilitation plans for brook trout, walleye, and lake sturgeon be published as one GLFC document that includes some information on status of the species in Lake Superior. The LSTC agreed that this is a reasonable expectation after the LSC has reviewed and commented on each of the plans.
The LSTC recommended that each of the rehabilitation plans should be ready for presentation to the LSC in March 1999. LSTC chairman Ebener will work with Nancy Auer and Michael Hoff to complete the sturgeon and walleye plans.
Agenda Item 4 - Age Determinations
of Lake Herring
Jeff Black from OMNR reported on comparisons of lake herring age composition data based on scales and otoliths. OMNR collected 500 pairs of scales and otoliths from lake herring caught during commercial and index netting in Thunder and Black bays during 1997?. Jeff reported that there were substantial differences in the estimated age composition of lake herring based on otoliths and scales after age 5. Scales appeared to dramatically underestimate the age of lake herring compared to otoliths. Otoliths showed lake herring up to 19 years old. Jeff reported that the age compositions from scales missed the 1984 year class and appeared to underage the fish, but the otoliths did not. Otoliths did a better job of showing year class strength based on USGS bottom trawls than did scales in each area and mesh size. There was a suggestion that we have a workshop for the individuals ageing fish in each agency so they can discuss the topic among themselves.
Conclusion: Otoliths are much better than scales at ageing
lake herring. Lake herring are
much longer lived than we imaged. Agencies should use otoliths to age lake herring,
particularly lake herring caught in commercial fisheries since these will be large-size fish.
Agenda Item 5 - Observation
on Lake Herring Year Class Strength
Stephen Schram distributed a handout illustrating catches of lake herring made in beach seines in the Duluth/Superior Harbor from 1980 through 1998. WiDNR caught young-of-the-year lake herring in 1984 when that year class was large, yearling lake herring in 1990 when the 1989 year class was large, and young-of-the-year herring again in 1998. Otherwise, no lake herring were caught in the seine hauls in the other years. The implication is that the 1998 year class of lake herring may have experienced good survival as in 1984 and 1989.
Agenda Item 6 - Fluctuations
in Abundance of Lake Herring
Henry Quinlan, Mike Hoff, and Ron Kinnunen conducted a literature review of lake herring and other coregonid populations around the world. The review evaluated variations in year class strength of Coregonus artedi, C. albula, C. autumanalis, C. clupeaformis, and C. lavaretus. The literature review found that variation in year class strength of lake herring in Lake Superior was larger than variation in year class strength of other coregonid populations from other lakes around the world. Mike, Henry, and Ron found in the review that no single or group of predictors could be used for determining when a large year class of coregonids will be produced. Environmental and inter-specific factors were named a large part of the time (1/4 to 1/2) as causing variations in year class strength of coregonids. Several studies reported that very large year classes were produced by very small populations of adults. In some studies there were direct relationships between egg deposition and early larval studies and adult abundance, but that relationship broke down at larger larval sizes.
Based on comparisons of scale and otolith ages and the literature review, the LSTC has reached the following conclusions:
1. Lake herring in Lake Superior are substantially older than we initially
had thought and are much longer lived.
2. Apparent stability of year class strength in the past may have been due to the inability to accurately age lake herring, thus the historic variation in year class strength may have been much larger than indicated by the available data based on scale ages.
3. We should expect large variations in year class strength of lake herring.
4. Variation in year class strength in Lake Superior appeared to be greater than that of other coregonids from other lakes around the world.
5. Environmental and inter-specific factors were named a larger number of times as causing the variation in year class strength of coregonids.
6. In some instances very large year classes were produced by very small populations of adults.
The LSTC would like to stress to the LSC that Variation in recruitment of lake herring is normal and to be expected, but we are worried that the lack of reproduction is not providing the number of small lake herring for consumption by lake trout and other predators that are normally needed for reasonable growth and there will not be enough herring to sustain commercial fisheries. The LSTC agreed to present our finding to the LSC in a series of presentations following the methods used by the LSTC to address our charge. Presentations will be as follows:
Present year class strength v. historic - Chuck Bronte
Scale v. otolith ages - Jeff Black
Historic age composition of the commercial harvest - Stephen Schram
Literature review - Henry Quinlan
Conclusions - Ebener
Agenda Item 7 - Biomass
of lake herring
Chris Harvey summarized the acoustics work conducted in the western arm of Lake Superior. The survey was a cooperative effort involving the UW-Madison, EPA, MnDNR, WiDNR, and USGS. The acoustic pings were integrated with a linear regression model from Lake Michigan that relates acoustic pings to length of fish. Length distributions based on acoustics were similar overall to that based on trawl catches. At Eco-region 1 near Duluth the mean density of pelagic fishes was 0.8 g/m2, with most fish being found near the bottom and near the surface. In Eco-region 2 along the more northern shore of Minnesota mean density of pelagic fishes was 0.5 g/m2 and most fish were found in 40-60 meters. At Eco-region 3 within the Apostle Islands mean density of pelagic fishes was 2.0 g/m2 and most fish were found near the bottom or near the surface. There were not many fish in mid water in Eco-region 3. All these acoustic surveys were based on night time transects. In daytime surveys all the fish go to bottom except for small amounts of fish near the surface.
Mid water trawls catches were composed of mainly lake herring and some C. kiyi at all depths in Eco-regions 1 and 2. Very few smelt were caught in Eco-regions 1 and 2. In comparison, trawl catches in the Apostle Islands were made up primarily of smelt and bloaters. In Eco-region 1 mid-water trawl catches showed mainly smelt near the surface, herring and C. kiyi in mid-water, and no bloaters. Based on the acoustics survey the Lake Superior pelagic biomass (grams per square meter) is 3 to 6 times less than other Great Lakes.
The LSTC recognizes the need to implement acoustics surveys on Lake Superior and have agreed to make a recommendation to the LSC that acoustics work on Lake Superior be given high priority for funding.
Agenda Item 8 - Recruitment
of Lake Herring in Lake Superior
Tom Drummer from Michigan Technical University discussed the project he and others are involved in to determine the "spatial and temporal patterns in lake herring age-1 year class strength." The objective of their analysis is to build a predictive model of an index of lake herring age-1 year class strength using abiotic factors, primarily temperature. The researchers looked at synchrony to define spatial scales. Strong synchrony is a function of distance and temperature. Spatial scales were lakewide, regional, or trawl sites. Did time series analysis to estimate density-dependent factors. Would like feedback from the LSTC on his analysis. Also looked at wind index based on offshore buoy information. The researchers identified seven areas of Lake Superior with similar temperture regimes; northern Minnesota, southern Minnesota MN and western Wisconsin, the Apostle Islands, western Keweenaw Peninsula, Eastern Keweenaw Peninsula, central Michigan, and Whitefish Bay. The temperature data was patchy so there were only 73 usable surface water temperature profiles based on satellite images. Tom created an ANOVA model to relate temperature and CPUE of age-1 lake herring. For the catch data they used 47 trawl sites in U.S. waters during 1978-1994.
The researchers found stronger synchrony in CPUE among sites in the early part of the time series than in the later part of the time series. There was more variation in CPUE in time than between sites in the lake. Noise made up the largest part of the variation in CPUE among spatial units. There was strong synchrony among trawl sites. General recommendation is that could aggregate trawl sites without much problem. The synchrony over time was driven by temperature. All correlation analyzes of CPUE with temperature were negative, but not strongly related at lakewide and regional levels. The researchers did find a decline in CPUE at high surface water temperatures and that warmer sites had more fish. Also found a negative correlation in CPUE at differences of three years. The researchers conclusions are that;
1) strong synchrony may indicate the presence of a large scale abiotic
effect on lake herring,
2) surface water temperature data based on satellite images has problems and is costly to process,
3) should consider other available large scale weather indices, and
4) there appears to be a density dependent mechanism operating in recruitment of lake herring in Lake Superior.
Their next step is analyze large scale weather indices. The researchers
also looked at effects of wind combined with water temperature and these
variables together illustrated a good correlation with CPUE.
Agenda Item 9 - Fish Health
Michigan: Jim Peck reported that Michigan does not have a fish health monitoring program per se, but in 1998 Michigan did collect whitefish from their commercial fishery for BKD analysis. None of the whitefish collected in 1998 showed evidence of BKD, although we know that BKD is present in Lake Superior.
Minnesota: Don Schreiner provided a handout that describes fish disease preventative actions taken during 1998 in Minnesota waters of Lake Superior. Don reported that Minnesota does monitor the health of fish that come back to the French River weir each year. Minnesota has had fish test positive for BKD, particularly chinooks. The incidence of BKD in chinooks returning to the French River was 30% in 1996, over 40% in 1997, but only 17% in 1998.
Wisconsin: Stephen Schram reported on the fish health monitoring conducted in Wisconsin waters of Lake Superior. Wisconsin tests only steelhead and chinook salmon returning to the Brule River for a variety of diseases including BKD, viruses, whirling disease, enteric redmouth, and several other diseases.
USFWS: The Ashland Fishery Assistance Office was conducting a health index on wild lake trout, but that program ended several years ago. The USFWS hatchery program currently conducts a fish health profile on hatchery-reared lake trout at least twice before the fish are stocked.
Keweenaw Bay Band: Mike Donofrio reported that sculpins, steelheads, and creek chubs from Kelsey Creek were subjected to fish disease monitoring in 1998 and no evidence of disease was found in these fish. The resident fish in Kelsey Creek were tested for disease prior to stocking hatchery-reared brook trout in the stream.
The LSTC took no further action. There is some confusion among
the LSTC as to the purpose of this agenda item. Ebener reminded LSTC
members that Tom Gorenflo had written the chairmen of the upper lakes technical
committees requesting that each committee discuss fish health monitoring
issues on each lake. Ebener will report to the LSC on this issue
and ask for direction.
Agenda Item 10 - Growth
At the summer 1998 meeting Mark Ebener had agreed to develop some indices of lake trout growth for review by the LSTC. Mark reported that he did not have enough time to complete the task, but that he did begin the process. Mark provided a handout that summarized mean length of age-7 lean lake trout by political jurisdiction, and indices of ration, length distribution of prey eaten, and proportion of prey items in the diet of leans and siscowets caught in MI-7 during the spring of 1995-1998.
Historically, the LSTC has just used mean length at age 7 to describe growth of lean lake trout. The problem with the size at age data is that mean length at age 7 is probably more directly related to events that took place while the fish was age 0 to age 2 than to events that occurred when the fish was age 6, so we are looking at past growth and not current growth.
Mark suggested that the index of ration may be as good an indicator
of lake trout growth as any of the calculated values such as condition,
length-weight, or size at age. Index of ration is a statistic that
should be reported as part of the fish diet protocol adopted for Lake Superior.
Ration is calculated as the average weight of food in the stomach of lake
trout within a specific size interval, including those fish with empty
stomachs. Mark reported that he estimates weight of food in the stomach
as the difference between the weight of the whole stomach including food
items and the weight of the stomach after all contents have been removed.
|Index of ration
Mark reported that he found a progressive decline in indices of ration in both leans and siscowets from 1996 to 1998, and that the decline was more severe in leans than in siscowets. The average index of ration for wild lean lake trout of all sizes declined from 32.8 g in 1996 to 8.6 g in 1998 in MI-7. The average index of ration for siscowets declined from 28.8 g in 1996 to 13.9 g in 1998. Most of the ration data was for lake trout of 400-599 mm and 600-799 mm long. The index of ration for 400-599 mm lean lake trout declined from 24.8 g in 1996 to 5.8 g in 1998.
The size distribution of prey items in the diet of leans and siscowets from MI-7 shifted to smaller sizes from 1995 to 1998. When smelt and coregonines made up a large proportion of the diet of leans many of the prey eaten were larger than 100 mm long, but by 1998 very few prey items were longer than 100 mm. This was true for both leans and siscowets, although there were more larger prey items eaten by leans than siscowets.
The proportion by weight of various prey in the diet of leans became more diverse from 1996 to 1998 in MI-7. Rainbow smelt made up 77% and coregonines 13% by weight of the diet of leans in 1996. In 1997 the diet was composed primarily of smelt (16%), sticklebacks (13%), coregonines (42%), and salmonines (25%), while in 1998 the diet of leans was primarily smelt (22%), sticklebacks (14%), Mysis (28%), and terrestrial insects (27%).
The effects of changes in ration and prey composition by lake trout should be reflected in growth, fecundity, and rate of maturity of lake trout. The potential is that lake trout will produce fewer eggs per female and that the proportion of mature females at a given size will also change.
Agencies should try to collect fecundity data
from lake trout and estimate the proportion mature by
age or size. The later in the year eggs are collected for fecundity
estimates the more reliable the information. Eggs from green females
collected in October are probably the most appropriate for estimating
fecundity, but not many agencies conduct fall spawning assessments.
Agenda Item 11 - Update
Chris Harvey provided an update on the ECOSIM modeling effort being conducted at UW-Madison. The newest version of the ECOPATH model has herring, leans, and siscowets biomass pools split into adult and sub-adults and these models are now linked to each other by a stock-recruitment function. The pools of adults and sub-adults were split because of concern that the ecological effects of fishing and predation mortality were being muted or misrepresented. Chris also reported that Carl Walters is now working on a new version of the ECOPATH software that will be able to consider spatial complexities. Chris also told the LSTC that siscowets are higher than leans on the trophic food web in Lake Superior based on his isotope research.
Agenda Item 12 - Assignments
for LSC meeting
The LSTC decided to provide the following oral and written reports at the annual LSC meeting in Milwaukee on March 23-24, 1999. In the report of the LSTC Mark Ebener will include discussions on survival index of hatchery reared lake trout, lake trout population parameters for evaluating the need to stock lake trout, and the nuts and bolts of the brook trout, lake sturgeon, and walleye rehabilitation plans. The following reports will be made to the LSC in March 1999.
Report of the LSTC - Ebener
Lake herring recruitment - Quinlan, Bronte, Schram, Black, Ebener
Acoustics work - Doran Mason
Forage survey - Hoff or Bronte
Sea lamprey Control Update - Klar
Sea lamprey marking - Ebener
Lake trout workshop update - Christie and Ebener
Agency highlights - Ebener will talk to the LSC about agenda item
Agenda Item 13 - Habitat
Dr. Michael Jones of MSU wrote a memo to the LSTC describing his GLFC funding to develop models that couple estimates of habitat supply with fish population dynamics. Mike and his co-investigators feel that a tool with this perspective would be useful for developing defensible rationale for environmental objectives in support of fish community objectives. The researchers have chosen to use a case-study approach by developing models for three species with widely contrasting habitat requirements and life histories, and then using a comparison of these models to see whether any general principles emerge. Mike asked the LSTC to consider adding a one-day workshop to our summer 1999 to scope the Lake Superior lake trout habitat model. The LSTC accepted Mikes proposal to hold a one-day workshop in concert with our summer 1999 meeting. Anyone interested in a copy of a progress report on linking habitat supply to fish community objectives using a population dynamics approach which provides considerable detail about the task Mike Jones is involved in should contact either Mark Ebener or Mike Jones. Mark Ebener will supply Mike Jones with a copy of the LSTC discussion paper on fish community objectives.
Agenda Item 14 - Isle Royale
Jim Peck distributed a report on results of an angler survey of the Lake Superior waters near Isle Royale, Michigan in 1998. Funding for the creel survey was provided by the National Park Foundation to the Isle Royale National Park in the form of a $15,000 grant. The area around the island was divided into 14 different spatial units. Michigan DNR made one airplane flight each week to count fishing effort around the island. Angling effort was estimated based on boat counts made from the ferry vessel Voyageur II one day each week as the Voyageur circled Isle Royale. There were three interview clerks; one at Grand Portage, one on the Voyageur II, and another that did interviews on the Park Service vessel the Ranger while the vessel was traveling from Isle Royale to Houghton, Michigan. The flights and the creel clerks aboard the Voyageur II and at Grand Portage were paid for with the $15,000 grant. Mike Donofrio provided the clerk that interviewed anglers on the Ranger. Michigan DNR planned the survey and estimated the catch estimates. Jim reported that creel clerks did not collect biological data on the fish and that the creel clerks saw some of the fish harvested, but not all of them. The standard MiDNR creel survey form was used but creel clerks also recorded the number of fish released. The creel survey includes on the months of June, July, and August, the principal fishing months at Isle Royale.
Twelve of the 14 anticipated airplane flights were made to count fishing effort. A total of 856 boating parties were interviewed at Grand Portage, from the Voyageur, and on the Ranger. Slightly more than 29,000 boat hr. were estimated for Isle Royale waters. Clerks aboard the Voyageur and at Grand Portage accounted for 91% of the boating surveys. Non-charter anglers contributed 95% of the total number of anglers. Non-charter anglers were predominately from Michigan (42%) and Minnesota (53%).
Lake trout were the predominate fish harvested from the Isle Royale waters. Anglers reported catching 10,500 lake trout and they also released another 10,800 lake trout. Coho were the second most commonly harvested fish followed by northern pike, although northern pike were the second most commonly caught fish species. Non-charter anglers fished 62,200 hours and harvested 9,600 lake trout. Anglers fishing charter boats fished 3,148 hours and harvested 871 lake trout. Harvest rates were significantly higher for charter boat anglers than for non-charter anglers; 0.28 v. 0.15.
Jim Peck reported that there is no money to do the study again, but the estimated lake trout harvest in 1998 was similar to past estimates made in the 1980s and early 1990s. MiDNR conducted a mail survey in the late 1980's that estimated 6,500 lake trout were caught at Isle Royale. In the early 1990's the MiDNR again estimated from a post card survey that 2,000 lake trout were caught from Isle Royale waters.
On a related issue Chuck Bronte indicated that the USGS is proposing
to conduct a gill net survey of lake trout population around Isle Royale
in May 1999. Chuck asked if other agencies could provide assistance
with the survey. Bill Mattes from GLIFWC and Mike Donofrio from the
Keweenaw Bay Indian Community both can commit one staff member to help
with the survey. Chuck, Jim Peck, Mike Donofrio, and Jack Oelfke
will write a plan for conducting the study.
Agenda Item 15 - Diet Protocol
Don Schreiner raised the question of how to report diet information and whether or not we need to collect the diet data from seasons other than spring. There was a general consensus of the LSTC that diet information from seasons other than spring was important, but collecting that data was another matter. Don questioned whether diet information in being collected from the sport fishery in jurisdictions other than Minnesota, particularly from species other than lake trout. No other jurisdiction is collecting diet information as part of creel surveys. Don will continue to collect diet information from the sport fishery in Minnesota every five years.
Agenda Item 16 - Gear Selectivity
Don Schreiner informed the LSTC that Dr. Charles Anderson from MnDNR has been conducting gill net selectivity studies on lake trout in Minnesota and that Dr. Anderson is looking for data on catches of lake trout in other gear types in order to estimate selectivity towards lake trout. LSTC members and participants informed Don that they have no size information on lake trout caught in other gears in Lake Superior. The LSTC took no action on this agenda item.
Agenda Item 17 - Bait fish
Henry Quinlan informed the LSTC that the Michigan Bait Dealers Association has asked the MiDNR to open the bait fishery on Lake Superior. The bait fishery in Michigan waters is currently closed due to the potential harvest and transport ruffe as part of the harvesting operations. Prior to the arrival of ruffe Michigan waters of Lake Superior was open to the bait fishery.
Agenda Item 18 - Aquatic
Mark Ebener distributed two handouts to the LSTC that originally came from LSC member Bob Thomson. The first handout was a revised mailing list for LSTC members and participants that also included names and addresses of individuals from agencies with connections to the Bi-National Working Group. The second handout was a set of tables identifying agencies and individuals within each agency that are involved in monitoring the various aquatic community indicators within the four habitat categories of Lake Superior. Bob asked that each LSTC member and participant review the tables for correctness and provide those corrections to Mark Ebener since Bob Thomson is retiring at the end of January 1999.
Agenda Item 19 - Fish Community
Mark Ebener provided the LSTC with a handout summarizing the draft fish community objectives for Lake Superior tentatively adopted by the writing team. Ebener informed the LSTC that the drafting team has already written a first draft of fish community objectives that will be submitted to each agency for internal and public review.
Agenda Item 20 - Aquatic
Mark Ebener informed LSTC that the Bi-National Working Group for Lake Superior has reorganized itself into a number of different committees; habitat, aquatic community, terrestrial, human health, etc. The Working Group will be requesting that the LSC appoint the LSTC and it chairman as the aquatic community committee since LSTC members and participants conduct most of the monitoring of the aquatic community in Lake Superior. The aquatic community currently has no members and the LSC has made no decision regarding a new work assignment for the LSTC. Ebener asked if other LSTC members or participants were interested in attending one-half the aquatic community committee meeting in the advent the LSC decides to accept the Working Group recommendation. Don Schreiner, Mike Donofrio, and Bill Mattes have indicated they would be willing to assist Ebener.
Agenda Item 21 - Time and
Place of Summer 1999 Meeting
The LSTC decided to hold it summer 1999 meeting in Marquette at the Sea Lamprey Control Station on August 3-5, 1999. A second lake trout modeling workshop will take place during the summer meeting. LSTC members and participants should come prepared with data that can be used in a statistical catch at age analysis as there should be a working template available at the meeting for estimating lake trout stock size and mortality. The LSTC will also meet with Dr. Michael Jones to provide data for his habitat supply model. Gary Klar has agreed to take care of arrangements for the meeting.